/*
 * $Header: /l/extreme/cvs/codes/XPP3/java/src/java/xpath/org/xmlpull/v1/builder/xpath/jaxen/function/ext/EvaluateFunction.java,v 1.2 2005/08/11 22:44:02 aslom Exp $
 * $Revision: 1.2 $
 * $Date: 2005/08/11 22:44:02 $
 *
 * ====================================================================
 *
 * Copyright (C) 2000-2002 bob mcwhirter & James Strachan.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions, and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions, and the disclaimer that follows 
 *    these conditions in the documentation and/or other materials 
 *    provided with the distribution.
 *
 * 3. The name "Jaxen" must not be used to endorse or promote products
 *    derived from this software without prior written permission.  For
 *    written permission, please contact license@jaxen.org.
 * 
 * 4. Products derived from this software may not be called "Jaxen", nor
 *    may "Jaxen" appear in their name, without prior written permission
 *    from the Jaxen Project Management (pm@jaxen.org).
 * 
 * In addition, we request (but do not require) that you include in the 
 * end-user documentation provided with the redistribution and/or in the 
 * software itself an acknowledgement equivalent to the following:
 *     "This product includes software developed by the
 *      Jaxen Project (http://www.jaxen.org/)."
 * Alternatively, the acknowledgment may be graphical using the logos 
 * available at http://www.jaxen.org/
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE Jaxen AUTHORS OR THE PROJECT
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * ====================================================================
 * This software consists of voluntary contributions made by many 
 * individuals on behalf of the Jaxen Project and was originally 
 * created by bob mcwhirter <bob@werken.com> and 
 * James Strachan <jstrachan@apache.org>.  For more information on the 
 * Jaxen Project, please see <http://www.jaxen.org/>.
 * 
 * $Id: EvaluateFunction.java,v 1.2 2005/08/11 22:44:02 aslom Exp $
 */

package org.xmlpull.v1.builder.xpath.jaxen.function.ext;

import java.util.Collections;
import java.util.List;

import org.xmlpull.v1.builder.xpath.jaxen.XPath;
import org.xmlpull.v1.builder.xpath.jaxen.Context;
import org.xmlpull.v1.builder.xpath.jaxen.ContextSupport;
import org.xmlpull.v1.builder.xpath.jaxen.Function;
import org.xmlpull.v1.builder.xpath.jaxen.Navigator;
import org.xmlpull.v1.builder.xpath.jaxen.FunctionCallException;
import org.xmlpull.v1.builder.xpath.jaxen.function.StringFunction;

import org.xmlpull.v1.builder.xpath.saxpath.SAXPathException;

/**
 * <code><i>node-set</i> evaluate(<i>string</i>)</code> 
 *  
 * @author Erwin Bolwidt (ejb @ klomp.org)
 */
public class EvaluateFunction implements Function
{
    public Object call( Context context, List args )
        throws FunctionCallException
    {
        if ( args.size() == 1 ) {
            return evaluate( context, args.get(0));
        }

        throw new FunctionCallException( "id() requires one argument" );
    }

    public static List evaluate (Context context, Object arg)
        throws FunctionCallException
    {
        List contextNodes = context.getNodeSet();
        
        if (contextNodes.size() == 0)
            return Collections.EMPTY_LIST;
      
        Object contextNode = contextNodes.get(0);
        Navigator nav = context.getNavigator();

        String xpathString;
        if ( arg instanceof String )
            xpathString = (String)arg;
        else
            xpathString = StringFunction.evaluate(arg, nav);

        try {
            XPath xpath = nav.parseXPath(xpathString);
            ContextSupport support = context.getContextSupport();
            xpath.setVariableContext( support.getVariableContext() );
            xpath.setFunctionContext( support.getFunctionContext() );
            xpath.setNamespaceContext( support.getNamespaceContext() );
            return xpath.selectNodes( context.duplicate() );
        }
        catch ( SAXPathException e ) {
            throw new FunctionCallException(e.toString());
        }
    }
}

